Brown criticized Republicans and Donald Trump for denying what a majority of climate scientists say is a real phenomenon made worse by human intervention, that the planet's temperatures are rising and causing a multitude of natural disasters to worsen and sea levels to rise.

"Make no mistake, climate change is real," Brown said. "Trump says global warming is a hoax. I say Trump is a fraud."

"Trump says there's no drought in California. I say Trump lies," he added.

Brown continued, saying the nation needs to pursue clean, renewable sources of energy -- a policy he said will help stimulate the economy, not harm it, as Republicans have suggested.

"We have solar, wind, zero-emission cars, energy efficiency and, yes, a tax on carbon. Our economy in California is growing faster than almost any nation in the whole world," he said.

"They tell us we have to choose between saving the economy and saving the planet. Donald Trump and the climate deniers are wrong. Dead wrong."